Andair gas cap - leaking through key slot

[Rick_A]

My Andair gas caps leak through the slot in the cap for the key. Is this normal?

I've noticed it more on one side then the other but I don't know if the leaking side just has more fuel in the tank.

[dmaib]

Mine have been leaking through the key slot since day one. A bit of a disappointment given the expense of these otherwise very nice caps. Seems to happen when I really top the tanks off. Both sides leak equally. I leave the tanks down just a tiny bit when filling and that seems to stop or minimize the problem. Usually the tank I take off on does not leak and I have supposed that is because the level has gone down fairly quickly on that tank during taxi/runup/takeoff. If I see the other cap leaking during climb, I will switch to that tank for a few minutes if I am at an altitude/location where I am comfortable switching tanks. It stops pretty quickly when feed off that tank.

I bought mine from Van's and am not sure they are Andair, but they look like the same caps shown on the Andair site.

[jarvis]

this news makes me really glad that I spent that $mall $ortune on those puppies

[RV7Ron]

I've got my wing kit on order and have been looking at fuel cap options, this was one that I was considering so this is good information to know since I havent pulled the trigger yet. Anyone else having this problem with Andair caps? And, a little off topic, has anyone had any problems with the 'deluxe' version from Van's?

[kevinh]

Yes - those caps are made in Britain. If it is made in the UK and it moves, it is required by law to leak fluids.

(said by someone who loves his Mini Cooper)

[Kenny Gene]

I have a set, love them, but they have leaked all over my dark leading edge and my paint guy says he cannot get the stain off,, bummer!! Like I said, I love the locking caps, hate the leaking and stained wing. I have lots of pictures to prove it, but not smart enough to post.
Kenny Gene

[pmccoy]

Have any of you contacted Andair?

Do they acknowledge this as an issue, or have any ideas how to fix?

I bought a pair of these fuel caps, but have yet to get flying. This troubles me a bit. I don't want to have leaking fuel from my locking caps.....

[Rick_A]

I've never contacted Andair. Based on the replies, it seems that the small leak is not that unusual.

In all fairness, it's mostly just an annoyance. Once a little fuel is burned off, the leaking stops. I didn't notice it as much when my plane was unpainted. Now that the wings are white, the blue dye is very noticeable.

On the plus side, I suppose if my fuel vent ever gets clogged, the leak is a backup vent!

[luv2flypilot]

Mine also leak a bit when the tanks are completely full. I also did not notice it as much until my airplane was painted. Luckily my wings are painted dark blue in the front part of my wing so it is not too bad on the eyes when it does leak a bit. Now I typically fill up the tanks to around 19 to 20 gallons each and have not had anymore problems. Another suggestion is keeping a good coat of wax on the wings. I purchased some wax made by Rejex that was recommended by my painter and the bugs and fuel stains seem to just wipe off pretty easily. I had to use some goof off and a bit of elbow grease to get them off before I put on a good coat of wax. The Rejex also makes for easy clean up on my belly from the smoke oil from my smoke system. I would highly recommend it.

http://www.rejex.com/rejex.html

[frazitl]

Andair pressure tested one that I sent back, and on return it was definitely better. I'm convinced that part of the problem is with my QB wings routing of the vent tube. It is in front of the fuel cap and not bent up as close as possible to the top skin. I think they should be routed behind the fuel cap, at least for the ground attitude on my 7A. Maybe a Taildragger would be better in front.

Anyway, what I think is happening is that a slug of fuel gets in my vent line when I really top it off, creating a positive pressure in the tank as the fuel warms up a bit. With the bottom of the locking cap swimming in fuel, fuel gets pushed up through the key mechanism. Running the engine on each tank after filling or blowing the slug of fuel out of the vent line with the cap off helps (don't suck!). Who knows, maybe the small leak thru the key hole will prevent paint popping over the tank rivets.

Best solution is just to not top off that last inch. QB builders should try to bend the vent tube up as far as possible before gluing the Andair cap rings in. Slow builders should think about where they place the tank end of their vent tube especially if using the locking caps...